The sleuthing is far from elementary in Sherlock Holmes: A Game of Shadows, Guy Ritchie’s action-packed sequel to his 2009 reinvention of Sir Arthur Conan Doyle’s fictional detective. The dense narrative taxes what Hercule Poirot referred to as the “little grey cells”, connecting minuscule clues in Holmes’s mind through high-speed flashbacks in a style that will be familiar to fans of the TV series CSI: Crime Scene Investigation. Sinewy plot strands will probably tie younger audiences in knots.

For all its intellectual rigour, the film often feels like a series of action set-pieces which have been bolted together. Stunts are orchestrated at breakneck speed by Ritchie, whose repeated use of slow-motion bloats the film’s cumbersome running time.

Holmes (Robert Downey Jr) has cut a swathe through the criminal fraternity of late-19th-century London aided by trusty sidekick Dr John Watson (Jude Law), who is bidding farewell to crime-solving to marry Mary Morstan (Kelly Reilly). Newspapers are filled with headlines about anarchist bombings in Strasbourg and Vienna, the apparent overdose of a Chinese opium dealer and the death of an American steel magnate.

Holmes deduces these events are linked to Professor James Moriarty (Jared Harris) and the sleuth persuades Watson to join him on one final globe-trotting adventure. En route, the pair encounter gypsy fortune teller Sim (Noomi Rapace) and Holmes’s brother Mycroft (Stephen Fry), who is well-connected in the British government.

A bruising battle of wits with Moriarty becomes personal when the diabolical professor promises to make Watson and his new wife suffer for Holmes’s meddling. “When two objects collide, there is always damage of a collateral nature,” threatens the scholar, who is protected by a sharp-shooting lackey, Col Moran (Paul Anderson).

The film is a sporadically entertaining jaunt. Downey Jr and Law ease back into familiar roles as the quixotic genius and his strait-laced foil, Rapace is suitably feisty in her first English-speaking role and Harris chews on every syllable with menacing intent. Eddie Marsan and Geraldine James reprise their roles as Inspector Lestrade and long-suffering landlady Mrs Hudson respectively, but neither is afforded sufficient screen time to make an impact.

There are some sparkling comic interludes, and Fry is a delight too as pompous, pontificating Mycroft, including a hysterical sequence, which sees him wander naked about his home, sparing his blushes (and ours) with strategically placed furnishings. Thank heavens for small vases.

In Alvin and the Chipmunks: Chipwrecked Dave (Jason Lee) heads off on a luxury cruise with singing critters Alvin (voiced by Justin Long), Simon (Matthew Gray Gubler) and Theodore (Jesse McCartney) and the feisty Chipettes — Britney (Christina Applegate), Eleanor (Amy Poehler) and Jeanette (Anna Faris). As usual, Alvin gets into various scrapes, incurring the wrath of the ship’s captain and former manager Ian (David Cross), who works as the onboard entertainer. While Dave takes a nap, Alvin and the gang take flight on a kite and are blown on to a tropical island with an active volcano. While the chipmunks return to nature, Dave and Ian race against time to rescue the animals.

Chipwrecked lacks the charm and energy of the earlier films and stranding the animals on an island is a flimsy contrivance to force Alvin to grow up. The digitally rendered critters warble at regular intervals to stave off our boredom and the Chipettes have their moment in the spotlight when they challenge three feisty femmes to a dance-off in the ship’s disco.

Lee is reduced to screaming Alvin’s name whenever the titular chipmunk gets into trouble, while the two scriptwriters casually mix pop culture references with the obligatory toilet humour.